>Hon er maer, ok henni thjona thaer er meyjar andask.
This might be easier to understand if the word order
is changed to the equivalent:
"Hon er mær ok þær er andask meyjar þjóna henni."
hon she
er is
mær maiden
ok and
þær they (feminine)
er who
andask die
meyjar maidens
þjóna serve
henni her
It seems that a countryman of mine already posted
a grammatical analysis so I'll let this do.
Kveðja,
Haukur